Microtubule associated proteins (MAPs) are of biological interest because they are important in maintaining the structural organization and stability of the microtubular cytoskelton. The proposed research is aimed at isolating genes which encode MAPs in higher plants, with a particular emphasis upon the eventual determination of how these proteins function in plant cells. The proteins belonging to one group of mammalian MAPs, which includes MAP2, tau and MAP4, all show a high degree of protein sequence conservation within a carboxy-terminal domain that serves to bind microtubles. We hypothesize that these conserved sequences are also present in plant MAP proteins. Our preliminary data showing hybridization between a cDNA encoding the conserved region of mouse MAP2 and genomic DNA from Arabidopsis thalian supports this hypothesis. We propose to isolate full-length MAP cDNA clones from Arabidopsis. One means of confirming whether or not these cDNAs represent true MAP ge nes will be to compare their nucleotide and derived amino acid sequences with those of known mammalian MAPs. We propose to use the University of Wisconsin GCG sequence analysis programs for these sequences comparisons. This and other aspects of this project will extend the cellular biological knowledge of the plant cytoskeleton and its functions within the cell. It will provide important information about a group of proteins where there is much speculation but little documentation of their functions during critical times in plant development.